CN107717955B

CN107717955B - Space four-degree-of-freedom inspection mechanical arm and control system and control method thereof

Info

Publication number: CN107717955B
Application number: CN201710908739.6A
Authority: CN
Inventors: 吕宏宇; 陈晗; 丁昳婷; 劳冠清; 李雄峰
Original assignee: Technology and Engineering Center for Space Utilization of CAS
Current assignee: Technology and Engineering Center for Space Utilization of CAS
Priority date: 2017-09-29
Filing date: 2017-09-29
Publication date: 2024-03-19
Anticipated expiration: 2037-09-29
Also published as: CN107717955A

Abstract

The invention relates to a four-degree-of-freedom inspection mechanical arm, a control system and a control method thereof, wherein the inspection mechanical arm is arranged at the top end of a load center frame; the device comprises an image acquisition device, a telescopic arm, a first rotating joint, a second rotating joint and a linear driving arm, wherein the telescopic arm is horizontally arranged, one end of the telescopic arm is rotationally connected to the top end of a load center frame through the first rotating joint, and the other end of the telescopic arm is vertically rotationally connected with the upper end of the linear driving arm through the second rotating joint; the image acquisition device is connected to the linear driving arm in a sliding manner and moves up and down under the driving of the linear driving arm. According to the four-degree-of-freedom inspection mechanical arm, the control system and the control method thereof, the circumferential rotation and the linear operation are combined, so that the inspection movement space can be traversed without dead angles, the inspection movement space can reach a preset position quickly and accurately in the working range, the inspection movement space can be stably kept at a target position, and the image can be photographed or recorded through the image acquisition device carried at the tail end.

Description

Space four-degree-of-freedom inspection mechanical arm and control system and control method thereof

Technical Field

The invention relates to the field of space robot control, in particular to a four-degree-of-freedom inspection mechanical arm, a control system and a control method thereof.

Background

With the rapid development of aerospace industry in China, the requirements for space manipulator are continuously increased. According to different installation positions, the space manipulator can be divided into two types of manipulator in the cabin and manipulator outside the cabin. The mechanical arm in the cabin is used for mostly serving tasks such as grabbing, maintaining and replacing equipment in the spacecraft, and is small in working range and physical size and flexible in operation. The cabin outer mechanical arm is mainly used for the assembly, maintenance and fuel supply of a spacecraft, space detection, space experiment and other works, has larger difference in configuration according to different action objects and task demands, has different degrees of freedom from five, six to tens of degrees of freedom, and spans several meters to tens of meters in arm length.

The space manipulator is a complex system which relates to a plurality of subjects and a plurality of technologies, has higher and higher requirements on working performances such as reliability, service life and the like, and the required control precision is improved day by day according to different experimental purposes. In the working process of the space manipulator, a great amount of time is needed to restrain vibration, and particularly in the space condition, no air damping exists, and the disturbance of the structure is difficult to control. Thus, precise position and torque control of the various joints of the space manipulator is a challenging problem.

Disclosure of Invention

The invention aims to solve the technical problem of providing a four-degree-of-freedom inspection mechanical arm, a control system and a control method thereof aiming at the defects of the prior art.

The technical scheme for solving the technical problems is as follows: the four-degree-of-freedom inspection mechanical arm is arranged at the top end of the load center frame; the device comprises an image acquisition device, a telescopic arm, a first rotating joint, a second rotating joint and a linear driving arm, wherein the telescopic arm is horizontally arranged, one end of the telescopic arm is connected to the top end of the load center frame through the first rotating joint in a rotating way, and the other end of the telescopic arm is connected with the upper end of the linear driving arm through the second rotating joint in a vertical rotating way; the image acquisition device is connected to the linear driving arm in a sliding manner and moves up and down under the driving of the linear driving arm.

The beneficial effects of the invention are as follows: according to the cruise mechanical arm, the circumferential rotation and the linear operation are combined, so that the inspection movement space can be traversed without dead angles, the inspection movement space can reach a preset position quickly and accurately in the working range, the inspection movement space can be stably kept at a target position, and then photographing or video recording is carried out through an image acquisition device carried at the tail end.

On the basis of the technical scheme, the invention can be improved as follows.

Further, the first rotary joint comprises a first motor, a speed reducer, a switching disc and a first circular grating encoder for recording the tail end speed and the position of the speed reducer, the first motor is fixedly installed at the top end of the load center frame, a motor shaft of the first motor is fixedly connected with the speed reducer coaxially, an output shaft of the speed reducer is fixedly connected with the switching disc coaxially, and the first circular grating encoder is fixed at the lower end of the switching disc.

The beneficial effects of adopting the further scheme are as follows: the speed and position feedback of the switching disc can be realized through the circular grating encoder, and the rotation precision can be improved and the output torque can be increased by adopting a structure of matching the motor and the speed reducer.

Further, the first rotating joint further comprises a shell and a base, wherein the base is horizontally sleeved above the first motor and fixed at the top end of the load center frame, and a motor shaft of the first motor penetrates out from the upper part of the base; the shell is cylindrical and coaxially sleeved outside the speed reducer, the lower end of the shell is fixed on the base, and the upper end of the shell forms a step for accommodating the adapter plate; the circular grating ruler of the first circular grating encoder is fixed at the lower end of the switching disc, and the grating reading head of the circular grating ruler is fixed on the step.

The beneficial effects of adopting the further scheme are as follows: through setting up shell and base, make the connection of reduction gear and motor inseparabler stability.

Further, the first rotating joint further comprises a first bearing, wherein an outer ring of the first bearing is coaxially fixed on the inner wall in the shell, and an inner ring of the first bearing is coaxially fixed on an output shaft of the speed reducer; the output shaft of the speed reducer is coaxially and rotatably connected with the shell through the first bearing.

The beneficial effects of adopting the further scheme are as follows: by arranging the first bearing, the radial stability of the output shaft of the speed reducer can be effectively improved.

Further, a through hole is formed in the center of the adapter plate, an annular boss is formed by extending the inner wall of the through hole inwards, and an output shaft of the speed reducer is arranged in the through hole in an upward fit mode and is fixed on the lower surface of the annular boss through a locating pin.

The beneficial effects of adopting the further scheme are as follows: through set up a through-hole in the switching dish center to form an annular boss at the through-hole inner wall, can effectively guarantee the concentricity of switching dish and reduction gear output shaft.

Further, the speed reducer is a harmonic drive speed reducer.

Further, the telescopic arm comprises a driving section, a moving section and a first linear grating encoder for recording horizontal movement displacement of the moving section, the driving section is fixed on the adapter plate, the moving section is coaxially sleeved on the driving section and can linearly move under the driving of the driving section, and one end of the moving section, which is far away from the driving section, is fixedly connected with the outer wall of the second rotary joint; the linear grating ruler of the first linear grating encoder is attached to the moving section along the moving direction of the moving section, and the grating reading head of the linear grating ruler is fixed on the driving section.

The beneficial effects of adopting the further scheme are as follows: the telescopic arm adopts a mode that the driving section and the moving section are combined, so that linear movement in the horizontal direction can be realized, the lengths of the driving section and the moving section can be adjusted according to the needs, and any working position which needs to be reached can be met.

Further, the driving section comprises a second motor, a first screw rod and a positioning shell, an output shaft of the second motor is fixedly connected with one end of the first screw rod, and the second motor is fixed at one end of the positioning shell;

the moving section comprises a first screw nut and a sleeve, the first screw nut is in threaded connection with the first screw, one end of the first screw nut, which is far away from the second motor, is fixedly connected with one end of the sleeve, and the sleeve is sleeved on the first screw and is positioned on the inner side of the positioning shell;

The first lead screw is driven by the second motor to rotate, and the first lead screw nut is driven to push the sleeve to linearly move along the positioning shell.

The beneficial effects of adopting the further scheme are as follows: the linear displacement is changed in a mode of adopting the screw rod and screw rod nut to be matched, the structure is simple, and the stroke is easy to control.

Further, a guiding limiting piece is fixed at one end of the positioning shell, far away from the second motor, two limiting blocks are respectively fixed at two ends of the sleeve, and a first linear guide rail arranged along the length direction of the sleeve is fixed on the sleeve; the guide limiting piece is connected to the first linear guide rail in a sliding mode.

The beneficial effects of adopting the further scheme are as follows: through setting up direction locating part, stopper and first linear guide, prevent that the sleeve from sliding out effective scope on first linear guide.

Further, a dust cover is fixed on the second motor, the dust cover is sleeved on a section of the first screw rod, which is close to the second motor, and the inner wall of the dust cover is rotationally connected with the first screw rod through a second bearing.

The beneficial effects of adopting the further scheme are as follows: through setting up the shield to set up the second bearing in the shield, make the circumferential movement of first lead screw more nimble convenient.

Further, one end of the first screw rod, which is far away from the second motor, is sleeved with a ball bearing sleeve, and the ball bearing sleeve is in rolling connection with the inner wall of the sleeve.

The beneficial effects of adopting the further scheme are as follows: through the ball axle sleeve is established to the one end cover that keeps away from the second motor at first lead screw, ball axle sleeve and outside sleeve cooperation, both can play the supporting role to first lead screw end, can make first lead screw realize carrying out the relative motion of two degrees of freedom of rotation and axial in the sleeve again.

Further, the second rotary joint comprises a turbine, a worm meshed with the external teeth of the turbine, a shell, a third motor and a second circular grating encoder for recording the rotation speed and the position of the turbine, wherein the turbine is vertically arranged; the outer side wall of the shell is fixed on one end of the telescopic arm far away from the first rotary joint, the third motor is fixed on the shell, a motor shaft of the third motor is fixedly connected with the worm in a coaxial way, and the position, close to the lower end, of the outer wall of the turbine is rotationally connected with the inner wall of the shell through an axial bearing; the circular grating ruler of the second circular grating encoder is coaxially fixed on the outer wall of the circumference side of the turbine, and the grating reading head of the circular grating ruler is fixed on the inner wall of the shell; the lower end of the turbine is fixedly connected with the upper end of the linear driving arm.

The beneficial effects of adopting the further scheme are as follows: through adopting the mode that turbine worm combines to carry out circumference transmission, the structure is more nimble, and the transmission is more convenient and reliable.

Further, the linear driving arm comprises a fourth motor, a shell, a second screw rod nut, a second linear guide rail and a second linear grating encoder for recording the position of the image acquisition device, the upper end of the shell is fixedly connected with the lower end of the turbine, and the fourth motor is fixed at the upper end of the shell and is positioned in the turbine; the second linear guide rail is fixed on the inner wall of the shell and is vertically arranged, the second lead screw is vertically arranged in the shell, the upper end of the second lead screw is coaxially and fixedly connected with the output shaft of the fourth motor, and the second lead screw nut is in threaded connection with the second lead screw and is in sliding connection with the second linear guide rail; the image acquisition device is fixed on one side wall of the screw nut, which is far away from the second linear guide rail.

The beneficial effects of adopting the further scheme are as follows: the image acquisition device is driven in the vertical direction by adopting a mode of matching the screw rod with the screw rod nut, so that the driving mode is flexible and easy to realize.

Further, a through hole which penetrates through the turbine from top to bottom is formed in the turbine, and the fourth motor is located in the through hole, and an output shaft of the fourth motor extends out of the lower end of the through hole and is fixedly connected with the upper end of the second screw rod.

The beneficial effects of adopting the further scheme are as follows: the turbine adopts the cavity design, makes the fourth motor of linear drive arm can directly pass the turbine and be connected with the second lead screw, has saved the space that second revolute joint and linear drive arm occupy to the maximum extent.

Further, a cover body and a positioning block are respectively fixed on the inner sides of the upper end and the lower end of the shell, and the two ends of the second screw rod are respectively connected with the inner wall of the cover body and the positioning block in a rotating way through a bidirectional bearing and a radial bearing.

The beneficial effects of adopting the further scheme are as follows: through setting up lid and locating piece to connect the both ends of lead screw on lid and locating piece through two-way bearing and radial bearing respectively, improved the radial positioning effect at lead screw both ends.

The other technical scheme for solving the technical problems is as follows:

a control system of four-degree-of-freedom inspection mechanical arm, which is used for controlling the inspection mechanical arm in the technical scheme, and comprises: the device comprises a processing unit, a conversion unit, an encoder interface unit, a Hall interface unit, a rotation interface unit, a current acquisition unit and a motor driving unit, wherein:

The encoder interface unit is connected with the inspection mechanical arm and is used for collecting the position information of the inspection mechanical arm;

the Hall interface unit and the rotary interface unit are respectively connected with a motor for controlling the movement of the inspection mechanical arm and are used for acquiring speed information of the motor;

the current acquisition unit is connected with the motor and used for acquiring current information output by the motor;

the conversion unit is respectively connected with the encoder interface unit, the Hall interface unit, the rotary-transformer interface unit and the current acquisition unit and is used for carrying out format conversion on the position information, the speed information and the current information;

the processing unit is respectively connected with the upper computer and the conversion unit and is used for communicating with the upper computer, and the control quantity for controlling the movement of the inspection mechanical arm is obtained according to the position information, the speed information and the current information after format conversion;

the conversion unit is also connected with the motor driving unit and is used for converting the control quantity format and then transmitting the control quantity format to the motor driving unit;

the motor driving unit is connected with the motor and used for controlling the motor according to the control quantity after format conversion so as to enable the inspection mechanical arm to move.

The beneficial effects of the invention are as follows: according to the control system of the four-degree-of-freedom inspection mechanical arm, provided by the invention, the encoder interface unit, the Hall interface unit, the rotary interface unit and the current acquisition unit are used for respectively acquiring the position information, the speed information and the current information of the control system, calculating the control quantity for controlling the movement of the inspection mechanical arm according to the position information, the speed information and the current information, controlling the motor according to the obtained control quantity, so that the inspection mechanical arm moves, flexible control of the inspection mechanical arm can be realized, the response is real-time, the dynamic performance is good, the direct-current brushless motor and the permanent magnet synchronous motor can be controlled in a compatible manner, and the application range is wider.

The control system provides various interface units, has the characteristics of high integration level, small size, high power density, flexible control, rich interfaces, various functions and intellectualization, and remarkably improves the power density, the integration level and the reliability of the inspection mechanical arm driver.

On the basis of the technical scheme, the invention can be improved as follows.

Further, the control system further includes: and the at least one isolation serial port unit is connected between the processing unit and the upper computer and is used for enabling the processing unit to carry out serial port communication with the upper computer.

The beneficial effects of adopting the further scheme are as follows: the serial port unit is isolated from the host computer for serial port communication, so that electromagnetic interference can be resisted, and the stability of the system is improved. And carry out serial communication through at least one isolation serial port unit and host computer, when isolation serial port unit breaks down, can in time carry out serial communication through other isolation serial port units and host computer, can improve the stability of system.

Further, the control system further includes: and the temperature acquisition unit is connected with the processing unit and is used for acquiring temperature information of the control system, and when the temperature information exceeds a preset temperature, the power supply of the control system is disconnected.

The beneficial effects of adopting the further scheme are as follows: the temperature information of the control system is acquired by the temperature acquisition unit, so that the power supply of the control system can be disconnected in time when the temperature of the control system is too high, and the safety and reliability of the control system are improved.

Further, the control system further includes: and the storage unit is connected with the processing unit and used for storing the position information, the speed information and the current information.

The beneficial effects of adopting the further scheme are as follows: the storage unit is used for regularly acquiring and storing the position information, the speed information and the current information, so that reliable data can be provided for manual diagnosis and equipment self-detection.

The other technical scheme for solving the technical problems is as follows:

a control method of a four-degree-of-freedom inspection mechanical arm is used for controlling the inspection mechanical arm in the technical scheme, and comprises the following steps:

acquiring position information of a patrol mechanical arm and controlling speed information and current information of a motor of the patrol mechanical arm;

performing format conversion on the position information, the speed information and the current information;

judging whether the motor is locked or abnormal in operation according to the position information, the speed information and the current information after format conversion;

if yes, stopping the motor; if not, a preset control algorithm is called, and a control quantity for controlling the movement of the inspection mechanical arm is calculated according to the position information, the speed information and the current information after format conversion;

and carrying out format conversion on the control quantity, and controlling the motor according to the control quantity after format conversion so as to enable the inspection mechanical arm to move.

On the basis of the technical scheme, the invention can be improved as follows.

Further, the acquiring the position information of the inspection mechanical arm, and controlling the speed information and the current information of the motor of the inspection mechanical arm specifically includes:

Receiving a control instruction sent by an upper computer;

and acquiring the position information of the inspection mechanical arm according to the control instruction, and controlling the speed information and the current information of the motor of the inspection mechanical arm.

Further, the calculating the control amount for controlling the movement of the inspection mechanical arm according to the processed position information, the processed speed information and the processed current information specifically includes:

performing current loop calculation according to the processed current information to obtain a current loop calculation result;

performing speed loop calculation according to the processed speed information to obtain a speed loop calculation result;

performing position loop calculation according to the processed position information to obtain a position loop calculation result;

and obtaining the control quantity for controlling the movement of the inspection mechanical arm according to the current loop calculation result, the speed loop calculation result and the position loop calculation result.

Further, the control method further includes: and acquiring a temperature value of a control system for controlling the inspection mechanical arm, and switching off a power supply of the control system when the temperature value is larger than a preset temperature value.

Further, the control method further includes: and acquiring and storing the position information, the speed information and the current information at preset time intervals.

Drawings

FIG. 1 is a schematic perspective view of a four-degree-of-freedom inspection robot arm according to the present invention;

FIG. 2 is a cross-sectional view of a first rotary joint of the present invention;

FIG. 3 is a cross-sectional view of a telescoping arm of the present invention;

FIG. 4 is a cross-sectional view of a second revolute joint of the present invention;

FIG. 5 is a schematic perspective view of a linear actuator arm according to the present invention;

FIG. 6 is a schematic top view of a linear actuator arm of the present invention;

FIG. 7 is a view of A-A of FIG. 6;

FIG. 8 is a schematic perspective view of a first lead screw with ball bearing sleeve according to the present invention;

FIG. 9 is a structural frame diagram of a control system for a four-degree-of-freedom inspection robot in accordance with the present invention;

FIG. 10 is a schematic structural diagram of a control system of a four-degree-of-freedom inspection robot according to the present invention;

fig. 11 is a flow chart of a control method of the four-degree-of-freedom inspection mechanical arm.

In the drawings, the list of components represented by the various numbers is as follows:

100. a first rotary joint; 101. a first motor; 102. a speed reducer; 103. an output shaft; 104. a switching disc; 114. a through hole; 124. a step; 134. an annular boss; 105. a first circular grating encoder; 106. a housing; 107. a base; 108. a first bearing;

200. a telescoping arm; 201. a second motor; 202. a moving section; 203. a drive section; 204. a first linear grating encoder; 205. a first lead screw; 206. positioning a shell; 207. a first lead screw nut; 208. a sleeve; 209. a guide limiting piece; 210. a limiting block; 211. a first linear guide rail; 212. a dust cover; 213. a second bearing; 214. a ball sleeve;

300. A second revolute joint; 301. a third motor; 302. a turbine; 303. a worm; 304. a housing; 305. a second circular grating encoder; 306. an axial load bearing; 307. a locking mechanism; 308. a through hole;

400. a linear driving arm; 401. a fourth motor; 402. a housing; 403. a second lead screw; 404. a second lead screw nut; 405. a second linear guide rail; 406. a cover body; 407. a positioning block; 408. a bidirectional bearing; 409. a radial bearing; 410. a second linear grating encoder;

500. an image acquisition device; 501. a base; 502. a lens; 503. a CCD module; 504. a light source; 505. a piezoelectric actuator;

600. a control system; 601. a processing unit; 602. a conversion unit; 603. an encoder interface unit; 604. a Hall interface unit; 605. a rotary interface unit; 606. a current collection unit; 607. a motor driving unit; 608. isolating the serial port unit; 609. a temperature acquisition unit; 610. and a memory cell.

Detailed Description

The principles and features of the present invention are described below with reference to the drawings, the examples are illustrated for the purpose of illustrating the invention and are not to be construed as limiting the scope of the invention.

As shown in fig. 1 to 5, a four-degree-of-freedom inspection mechanical arm of the present embodiment is mounted on the top end of a load center frame; the device comprises an image acquisition device 500, a telescopic arm 200, a first rotary joint 100, a second rotary joint 300 and a linear driving arm 400, wherein the telescopic arm 200 is horizontally arranged, one end of the telescopic arm 200 is rotationally connected to the top end of the load center frame through the first rotary joint 100, and the other end of the telescopic arm 200 is vertically rotationally connected with the upper end of the linear driving arm 400 through the second rotary joint 300; the image acquisition device 500 is slidably connected to the linear driving arm 400 and moves up and down under the driving of the linear driving arm 400. According to the cruising mechanical arm, circumferential rotation and linear operation are combined, so that the cruising movement space can be traversed without dead angles, the cruising mechanical arm can rapidly and accurately reach a preset position in a working range, can stably keep at a target position, and can take pictures or record videos through an image acquisition device carried by the tail end.

As shown in fig. 2, the first rotary joint 100 of the present embodiment includes a first motor 101, a speed reducer 102, a switching disc 104, and a first circular grating encoder 105 for recording the speed and the position of the end of the speed reducer 102, where the first motor 101 is fixedly installed at the top end of the load center frame, a motor shaft of the first motor 101 is fixedly connected with the speed reducer 102 coaxially, an output shaft 103 of the speed reducer 102 is fixedly connected with the switching disc 104 coaxially, and the first circular grating encoder 105 is fixed at the lower end of the switching disc 104. The speed and position feedback of the switching disc can be realized through the circular grating encoder, and the rotation precision can be improved and the output torque can be increased by adopting a structure of matching the motor and the speed reducer.

As shown in fig. 2, the first rotary joint 100 of the present embodiment further includes a housing 106 and a base 107, where the base 107 is horizontally sleeved over the first motor 101 and fixed on the top end of the load center frame, and a motor shaft of the first motor 101 passes through the base 107; the casing 106 is cylindrical and coaxially sleeved outside the speed reducer 102, the lower end of the casing 106 is fixed on the base 107, and the upper end of the casing 106 forms a step 124 for accommodating the adapter plate 104; the circular grating ruler of the first circular grating encoder 105 is fixed at the lower end of the adapter plate 104, and the grating reading head of the circular grating encoder is fixed on the step 124. Through setting up shell and base, make the connection of reduction gear and motor inseparabler stability.

As shown in fig. 2, the first rotary joint 100 of the present embodiment further includes a first bearing 108, an outer ring of the first bearing 108 is coaxially fixed on an inner wall in the housing 106, and an inner ring of the first bearing 108 is coaxially fixed on the output shaft 103 of the reducer 102; the output shaft 103 of the reducer 102 is rotatably connected coaxially with the housing 106 via the first bearing 108. By arranging the first bearing, the radial stability of the output shaft of the speed reducer can be effectively improved.

As shown in fig. 2, a through hole 114 is formed in the center of the adapter plate 104 in this embodiment, an inner wall of the through hole 114 extends inward to form an annular boss 134, and the output shaft 103 of the speed reducer 102 is disposed in the through hole 114 in an upward fit manner and is fixed on a lower surface of the annular boss 134 by a positioning pin. Through set up a through-hole in the switching dish center to form an annular boss at the through-hole inner wall, can effectively guarantee the concentricity of switching dish and reduction gear output shaft.

Specifically, the speed reducer 102 in this embodiment is a harmonic drive speed reducer, the first motor 101 in this embodiment is a brushless dc motor, and a motor shaft of the brushless dc motor is in key connection with the speed reducer 102, so that the power transmission accuracy is high. In addition, the first bearing 108 of the present embodiment adopts a double-row angular contact ball bearing, that is, the output shaft 103 of the speed reducer 102 is rotationally connected with the housing 106 through the double-row angular contact ball bearing, so that the stability of the output shaft of the speed reducer in the radial direction can be effectively improved.

As shown in fig. 3, the telescopic arm 200 of the present embodiment includes a driving section 203, a moving section 202, and a first linear grating encoder 204 for recording horizontal movement displacement of the moving section 202, where the driving section 203 is fixed on the adapter plate 104, the moving section 202 is coaxially sleeved on the driving section 203 and can linearly move under the driving of the driving section 203, and one end of the moving section 202 far away from the driving section 203 is fixedly connected with the outer wall of the second rotary joint 300; the linear grating ruler of the first linear grating encoder 204 is attached to the moving section 202 along the moving direction of the moving section 202, and the grating reading head thereof is fixed to the driving section 203. The telescopic arm adopts a mode that the driving section and the moving section are combined, so that linear movement in the horizontal direction can be realized, the lengths of the driving section and the moving section can be adjusted according to the needs, and any working position which needs to be reached can be met.

As shown in fig. 3, the driving section 203 of the present embodiment includes a second motor 201, a first screw 205, and a positioning housing 206, where an output shaft of the second motor 201 is fixedly connected to one end of the first screw 205, and the second motor 201 is fixed to one end of the positioning housing 206; the moving section 202 comprises a first screw nut 207 and a sleeve 208, the first screw nut 207 is in threaded connection with the first screw 205, one end of the first screw nut 207, which is far away from the second motor 201, is fixedly connected with one end of the sleeve 208, and the sleeve 208 is sleeved on the first screw 205 and is positioned on the inner side of the positioning shell 206; the first screw 205 is driven by the second motor 201 to rotate, and drives the first screw nut 207 to push the sleeve 208 to linearly move along the positioning housing 206. The linear displacement is changed in a mode of adopting the screw rod and screw rod nut to be matched, the structure is simple, and the stroke is easy to control.

As shown in fig. 3, a guiding and limiting member 209 is fixed at one end of the positioning housing 206 far away from the second motor 201 in this embodiment, two limiting blocks 210 are respectively fixed at two ends of the sleeve 208, and a first linear guide rail 211 arranged along the length direction of the sleeve 208 is fixed on the sleeve 208; the guiding and limiting piece 209 is slidably connected to the first linear guide rail 211. Through setting up direction locating part, stopper and first linear guide, prevent that the sleeve from sliding out effective scope on first linear guide.

As shown in fig. 3, a dust cover 212 is fixed on the second motor 201 of the present embodiment, the dust cover 212 is sleeved on a section of the first screw rod 205 near the second motor 201, and the inner wall of the dust cover is rotatably connected with the first screw rod 205 through a second bearing 213. Through setting up the shield to set up the second bearing in the shield, make the circumferential movement of first lead screw more nimble convenient.

As shown in fig. 3 and 8, a ball bearing sleeve 214 is sleeved on one end of the first screw 205 far away from the second motor 201, and the ball bearing sleeve 214 is in rolling connection with the inner wall of the sleeve 208. Through the ball axle sleeve is established to the one end cover that keeps away from the second motor at first lead screw, ball axle sleeve and outside sleeve cooperation, both can play the supporting role to first lead screw end, can make first lead screw realize carrying out the relative motion of two degrees of freedom of rotation and axial in the sleeve again.

One end of the first screw rod 205 is connected with a motor shaft of the second motor 201 through a key, and the second bearing 213 is an angular contact ball bearing; concentricity is ensured by two back-to-back angular ball bearings at the end of the first lead screw 205 near the second motor 201. The linear grating ruler of the first linear grating encoder 204 is attached to the lower portion of the sleeve, and the grating reading head of the linear grating ruler is installed in the guiding limiting piece 209.

As shown in fig. 4, the second rotary joint 300 of the present embodiment includes a turbine 302 vertically arranged, a worm 303 meshed with external teeth of the turbine 302, a housing 304, a third motor 301, and a second circular grating encoder 305 for recording the rotation speed and position of the turbine 302; the outer side wall of the casing 304 is fixed at one end of the telescopic arm 200 away from the first rotary joint 100, the third motor 301 is fixed on the casing 304, a motor shaft of the third motor 301 is fixedly connected with the worm 303 coaxially, and a position, close to the lower end, of the outer wall of the turbine 302 is rotatably connected with the inner wall of the casing 304 through an axial bearing 306; the circular grating ruler of the second circular grating encoder 305 is coaxially fixed on the outer wall of the circumference side of the turbine 302, and the grating reading head thereof is fixed on the inner wall of the casing 304; the lower end of the turbine 302 is fixedly connected to the upper end of the linear driving arm 400. Through adopting the mode that turbine worm combines to carry out circumference transmission, the structure is more nimble, and the transmission is more convenient and reliable.

As shown in fig. 5 and 7, the linear driving arm 400 of the present embodiment includes a fourth motor 401, a housing 402, a second screw 403, a second screw nut 404, a second linear guide rail 405, and a second linear grating encoder 410 for recording a position of the image capturing device, where an upper end of the housing 402 is fixedly connected to a lower end of the turbine 302, and the fourth motor 401 is fixed to an upper end of the housing 402 and is located in the turbine 302; the second linear guide rail 405 is fixed on the inner wall of the housing 402 and is vertically arranged, the second lead screw 403 is vertically arranged in the housing 402, the upper end of the second lead screw is coaxially and fixedly connected with the motor shaft of the fourth motor 401, and the second lead screw nut 404 is in threaded connection with the second lead screw 403 and is in sliding connection with the second linear guide rail 405; the image acquisition device 500 is fixed on a side wall of the second screw nut 404 away from the second linear guide 405. The image acquisition device is driven in the vertical direction by adopting a mode of matching the screw rod with the screw rod nut, so that the driving mode is flexible and easy to realize.

As shown in fig. 4, 6 and 7, the turbine of this embodiment is provided with a through hole 308 penetrating up and down, and the fourth motor 401 is located in the through hole 308, and an output shaft thereof extends from a lower end of the through hole 308 and is fixedly connected to an upper end of the second screw 403. Because the central axis of the turbine is also vertically arranged, the through hole on the turbine is actually coaxially arranged with the turbine, and the turbine adopts a hollow design, so that the fourth motor of the linear driving arm can directly penetrate through the turbine to be connected with the second screw rod, and the space occupied by the second rotary joint and the linear driving arm is saved to the greatest extent.

As shown in fig. 5, in this embodiment, a cover 406 and a positioning block 407 are respectively fixed on the inner sides of the upper and lower ends of the housing 402, and two ends of the second screw 403 are respectively rotatably connected with the inner wall of the cover 406 and the positioning block 407 through a bidirectional bearing 408 and a radial bearing 409. Through setting up lid and locating piece to connect the both ends of lead screw on lid and locating piece through two-way bearing and radial bearing respectively, improved the radial positioning effect at lead screw both ends.

As shown in fig. 5, the image capturing device 500 of the present embodiment includes a base 501, a lens 502, a CCD module 503, a light source 504, and a piezoelectric actuator 505, the base 501 is fixed on the second lead screw nut 404, the CCD module 503 is mounted on one side of the base 501, the lens 502 is mounted on the other side of the base 501, and the light source 504 and the piezoelectric actuator 505 are mounted on the lens 502.

The four-degree-of-freedom inspection mechanical arm can realize inspection and observation of load equipment in ground or space application by combining circumferential rotation and linear motion, and the mechanical arm has the advantages of randomly accessible inspection space, simple structure and high control precision.

As shown in fig. 9, which is a structural frame diagram of a control system 600 of a four-degree-of-freedom inspection robot according to the present invention, the control system 600 is configured to control the inspection robot in the above-mentioned technical solution, and the control system 600 includes: the processing unit 601 may use a DSP (Digital Signal Process, digital signal processing) chip, and is mainly used for communication with an upper computer, processing various feedback information sent by the conversion unit 602, controlling the inspection mechanical arm, the conversion unit 602 may use an FPGA (Field-Programmable Gate Array, field programmable gate array) chip, and may implement protocol conversion of the encoder interface unit 603, the rotary interface unit 605, and the hall interface unit 604, convert a fixed format protocol output by the sensor into useful position information, speed information, and current information, and send the useful position information, speed information, and current information to the DSP chip for control operation, and simultaneously convert a motor control amount sent by the DSP chip into PWM information, and perform driving control.

The units are described in detail below.

The encoder interface unit 603 is connected with the inspection robot and is used for collecting position information of the inspection robot. For example, the position information of each rotating joint, telescopic arm, driving arm and other structures of the inspection mechanical arm can be acquired, and the position information of a certain structure of the inspection mechanical arm can be determined and acquired through an image acquisition device and the like on the inspection mechanical arm.

The position information may include angle information of each joint of the inspection robot arm and position information of each arm, which participate in the control value calculation of the position loop.

The hall interface unit 604 and the rotary interface unit 605 are respectively connected with a motor for controlling the movement of the inspection mechanical arm and are used for collecting the speed information of the motor, and the speed information of the motor participates in the control operation of the speed loop, wherein the hall interface unit 604 is an auxiliary interface, so that the safety of the system can be improved.

The current collection unit 606 is connected with the motor and is used for collecting current information output by the motor, the current information participates in control operation of a current loop, and the current loop adopts a vector control mode for controlling exciting current to be zero.

That is, in the control system 600 provided in this embodiment, by adopting a control structure in which three closed loops of position, speed and current are connected in series, the three closed loops all adopt a conventional PID control method, the control parameters of the three loops can be independently adjusted, and the control frequency of the three loops decreases from inside to outside, which will be described in detail below.

The current loop is used as the innermost loop of the system, realizes the tracking of exciting current and torque current, and plays a role in inhibiting the interference of the back electromotive force action of the motor, the bus voltage fluctuation and the like. The desired input of the torque current component is given by the output of the speed loop, with the desired excitation current component always being zero. The current feedback is collected by a current sensor. The control frequency of the current loop designed in the system is 10kHz under the restriction of the current sampling speed, the inverter switching frequency and the controller calculation speed.

The speed loop is an intermediate loop of the system, enabling fast tracking of speed and suppressing load changes and the effects of disturbance torque on the control system 600. The desired value of the speed is given by the output of the position loop, and the feedback value is calculated after decoding by a rotary encoder mounted on the motor. The frequency of the speed ring is limited by the response speed of the motor and the measurement accuracy of the rotating speed, and the control frequency of the speed ring designed in the system is 1kHz.

The position ring is the outermost ring of the system, and accurate control of the position is realized. The position expectation is directly input by the master control, and the feedback is detected by the position encoder of the tail end. The control frequency of the position loop is 1kHz.

The conversion unit 602 is connected to the encoder interface unit 603, the hall interface unit 604, the rotation interface unit 605, and the current acquisition unit 606, respectively, for performing format conversion on the position information, the speed information, and the current information.

The processing unit 601 is respectively connected with the upper computer and the conversion unit 602, and is used for communicating with the upper computer, and obtaining a control amount for controlling the movement of the inspection mechanical arm according to the position information, the speed information and the current information after format conversion. After receiving the position information, the speed information, and the current information after the format conversion, the processing unit 601 corrects and normalizes each of the position information, the speed information, and the current information, and then performs the next processing.

It should be noted that, a control algorithm is pre-stored in the processing unit 601, the control algorithm is completed in an external interrupt service program of the processing unit 601, an external interrupt is generated by the conversion unit 602, after the external interrupt is generated, the external interrupt is sent to the processing unit 601 by the conversion unit 602, after the external interrupt is generated, the processing unit 601 reads the position information, the speed information and the current information processed by the conversion unit 602 through a bus, and carries out correction and standardization processing, then judges whether the motor is blocked or abnormal in operation according to the position information, the speed information and the current information, and if the motor is blocked or abnormal in operation, stops the motor; if not, continuing to control calculation of the position loop and the speed loop to obtain the control quantity, and then interrupting the exit.

The processing unit 601 also has functions of status monitoring, fault self-checking, and the like.

The conversion unit 602 is also connected to the motor driving unit 607 for transmitting the control amount after processing to the motor driving unit 607.

For example, the control amount may be converted into PWM information.

The motor driving unit 607 is connected to the motor and is used for controlling the motor according to the control amount to move the inspection mechanical arm.

The control amount received by the motor driving unit 607 is the control amount converted by the converting unit 602, for example, may be PWM information, and then the motor is driven according to the PWM information, so that the control of each joint and arm of the inspection robot arm may be achieved.

According to the control system 600 of the four-degree-of-freedom inspection mechanical arm, the encoder interface unit 603, the Hall interface unit 604, the rotary interface unit 605 and the current acquisition unit 606 are used for respectively acquiring the position information, the speed information and the current information of the control system 600, calculating the control quantity for controlling the movement of the inspection mechanical arm according to the position information, the speed information and the current information, controlling the motor according to the obtained control quantity, enabling the inspection mechanical arm to move, realizing flexible control of the inspection mechanical arm, responding to real-time and good in dynamic performance, being capable of compatibly controlling the DC brushless motor and the permanent magnet synchronous motor, and being wider in application range.

The control system 600 provides various interface units, has the characteristics of high integration level, small size, high power density, flexible control, rich interfaces, various functions and intellectualization, and remarkably improves the power density, the integration level and the reliability of the inspection mechanical arm driver.

As shown in fig. 10, a schematic structural diagram of a control system 600 of a four-degree-of-freedom inspection robot according to the present invention is shown, where the control system 600 is configured to control the inspection robot in the above technical solution, and includes: the processing unit 601, the conversion unit 602, the encoder interface unit 603, the hall interface unit 604, the rotary interface unit 605, the current acquisition unit 606, the motor driving unit 607, the isolation serial unit 608, the temperature acquisition unit 609, and the storage unit 610 are described in detail below.

The encoder interface unit 603 is connected with the inspection robot and is used for collecting position information of the inspection robot.

The Hall interface unit 604 and the rotary interface unit 605 are respectively connected with a motor for controlling the movement of the inspection mechanical arm and are used for acquiring speed information of the motor.

The current collection unit 606 is connected to the motor and is used for collecting current information output by the motor.

The processing unit 601 is respectively connected with the upper computer and the conversion unit 602, and is used for communicating with the upper computer, and obtaining a control amount for controlling the movement of the inspection mechanical arm according to the position information, the speed information and the current information after format conversion.

The conversion unit 602 is also connected to the motor driving unit 607 for converting the control amount format and transmitting to the motor driving unit 607.

The motor driving unit 607 is connected to the motor and is used for controlling the motor according to the control amount after format conversion to make the inspection mechanical arm move.

The isolation serial units 608 are connected between the processing unit 601 and the upper computer, and at least one isolation serial unit 608 is used for enabling the processing unit 601 to perform serial communication with the upper computer. By performing serial communication with the upper computer through the isolation serial unit 608, electromagnetic interference can be resisted, and the stability of the system can be improved.

For example, the number of the isolation serial units 608 may be 2, in the actual use process, only 1 isolation serial unit 608 may work, and the other one is used as a backup, serial communication is performed between at least one isolation serial unit 608 and the upper computer, and when the isolation serial unit 608 fails, serial communication can be performed between the other isolation serial units 608 and the upper computer in time, so that the stability of the system can be improved.

The temperature acquisition unit 609 is connected to the processing unit 601, and is used for acquiring temperature information of the control system 600, and when the temperature information exceeds a preset temperature, the power supply of the control system 600 is disconnected.

For example, the temperature of the circuit board in which the processing unit 601 and the conversion unit 602 are located in the control system 600 may be monitored. By collecting the temperature information of the control system 600 through the temperature collecting unit 609, when the temperature of the control system 600 is too high, the power supply of the control system 600 can be disconnected in time, and the safety and reliability of the control system 600 can be improved.

The storage unit 610 is connected to the processing unit 601 for storing position information, speed information, current information, and temperature information. By periodically collecting and storing position information, speed information, current information, and temperature information through the storage unit 610, reliable data can be provided for manual diagnosis and self-detection of equipment.

Preferably, the control system 600 may further include a power conversion unit 611 for converting a voltage input from a power source into a voltage required by other units to provide power support.

Through isolating serial ports and communicating with the host computer, the safety and stability of communication can be improved. And the temperature of the control system 600 is monitored by the temperature acquisition unit 609, so that when the temperature of the control system 600 is too high, the power supply of the control system 600 can be disconnected in time, and the safety and reliability of the control system 600 are improved. And stores various kinds of information through the storage unit 610, so that the subsequent monitoring of the operation of the control system 600 can be facilitated.

Fig. 11 is a schematic flow chart of a control method of the four-degree-of-freedom inspection mechanical arm according to the present invention, the method includes the following steps:

s1, acquiring position information of the inspection mechanical arm through sensors arranged on each shutdown and arm of the inspection mechanical arm, and acquiring and controlling speed information and current information of a motor of the inspection mechanical arm through a Hall interface unit, a rotary interface unit and a current acquisition unit.

S2, format conversion is carried out on the position information, the speed information and the current information by using the conversion unit, protocol conversion is realized, and the fixed format protocols output by each sensor and the Hall interface unit, the rotary interface unit and the current acquisition unit are converted into the position information, the speed information and the current information which are available to the processing unit.

And S3, the processing unit corrects and standardizes the received position information, speed information and current information, judges whether the motor is blocked or abnormal in operation according to the processed position information, speed information and current information, stops the motor if yes, and executes the next step if no.

S4, calling a preset control algorithm, and calculating a control quantity for controlling the movement of the inspection mechanical arm according to the position information, the speed information and the current information after format conversion.

S5, the conversion unit converts the control quantity into a format and converts the format into a signal which can be used by a driving motor, for example, the format can be converted into a PWM signal, and the motor is controlled according to the control quantity after format conversion to perform driving control, so that the inspection mechanical arm moves.

Preferably, before step S1, the following steps may be further included:

and receiving a control instruction sent by the upper computer.

And acquiring the position information of the inspection mechanical arm and controlling the speed information and the current information of the motor of the inspection mechanical arm according to the control instruction.

Preferably, in step S3, a control amount for controlling the movement of the inspection robot arm is calculated according to the processed position information, speed information and current information, and specifically includes the following steps:

and carrying out current loop calculation according to the processed current information to obtain a current loop calculation result.

And performing speed loop calculation according to the processed speed information to obtain a speed loop calculation result.

And performing position loop calculation according to the processed position information to obtain a position loop calculation result.

It should be noted that, the current loop adopts a vector control mode of controlling the exciting current to be zero, the three closed loops all adopt a traditional PID control method, the control parameters of the three loops can be independently adjusted, and the control frequency of the three loops is decreased from inside to outside.

Preferably, the method further comprises the following steps:

and acquiring a temperature value of a control system for controlling the inspection mechanical arm, and switching off a power supply of the control system when the temperature value is larger than a preset temperature value. The preset temperature value can be set according to actual requirements.

Preferably, the method further comprises the following steps:

position information, speed information and current information are acquired and stored at intervals of preset time intervals, and can be sent to an upper computer through the isolation serial port unit regularly so as to monitor the working state of the control system.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.

Claims

1. The control system of the space four-degree-of-freedom inspection mechanical arm is characterized by being used for controlling the four-degree-of-freedom inspection mechanical arm, wherein the four-degree-of-freedom inspection mechanical arm is arranged at the top end of a load center frame and comprises an image acquisition device, a telescopic arm, a first rotating joint, a second rotating joint and a linear driving arm, one end of the telescopic arm is horizontally arranged and is rotationally connected with the top end of the load center frame through the first rotating joint, and the other end of the telescopic arm is vertically and rotationally connected with the upper end of the linear driving arm through the second rotating joint; the image acquisition device is connected to the linear driving arm in a sliding way and moves up and down under the driving of the linear driving arm;

The control system includes: the device comprises a processing unit, a conversion unit, an encoder interface unit, a Hall interface unit, a rotation interface unit, a current acquisition unit and a motor driving unit, wherein:

2. The control system of the four-freedom-degree space inspection mechanical arm according to claim 1, wherein the first rotary joint comprises a first motor, a speed reducer, a switching disc and a first circular grating encoder for recording the tail end speed and the position of the speed reducer, the first motor is fixedly installed at the top end of the load center frame, a motor shaft of the first motor is fixedly connected with the speed reducer coaxially, an output shaft of the speed reducer is fixedly connected with the switching disc coaxially, and the first circular grating encoder is fixed at the lower end of the switching disc.

3. The control system of the four-freedom-degree space inspection mechanical arm according to claim 2, wherein the first rotating joint further comprises a shell and a base, the base is horizontally sleeved above the first motor and fixed at the top end of the load center frame, and a motor shaft of the first motor penetrates out from the upper side of the base; the shell is cylindrical and coaxially sleeved outside the speed reducer, the lower end of the shell is fixed on the base, and the upper end of the shell forms a step for accommodating the adapter plate; the circular grating ruler of the first circular grating encoder is fixed at the lower end of the switching disc, and the grating reading head of the circular grating ruler is fixed on the step.

4. The control system of the four-freedom-degree space inspection mechanical arm according to claim 3, wherein the first rotating joint further comprises a first bearing, an outer ring of the first bearing is coaxially fixed on an inner wall in the shell, and an inner ring of the first bearing is coaxially fixed on an output shaft of the speed reducer; the output shaft of the speed reducer is coaxially and rotatably connected with the shell through the first bearing.

5. The control system of a four-degree-of-freedom space inspection robot according to any one of claims 2 to 4, wherein a through hole is formed in the center of the adapter plate, an inner wall of the through hole extends inwards to form an annular boss, and an output shaft of the speed reducer is upwardly adapted to be inserted into the through hole and is fixed on the lower surface of the annular boss through a positioning pin.

6. The control system of a four-degree-of-freedom spatial inspection robot according to any one of claims 2 to 4, wherein the decelerator is a harmonic drive decelerator.

7. The control system of the four-freedom-degree space inspection mechanical arm according to any one of claims 2 to 4, wherein the telescopic arm comprises a driving section, a moving section and a first linear grating encoder for recording horizontal movement displacement of the moving section, the driving section is fixed on the adapter plate, the moving section is coaxially sleeved on the driving section and can linearly move under the driving of the driving section, and one end of the moving section, which is far away from the driving section, is fixedly connected with the outer wall of the second rotary joint; the linear grating ruler of the first linear grating encoder is attached to the moving section along the moving direction of the moving section, and the grating reading head of the linear grating ruler is fixed on the driving section.

8. The control system of the spatial four-degree-of-freedom inspection mechanical arm according to claim 7, wherein the driving section comprises a second motor, a first screw rod and a positioning shell, an output shaft of the second motor is fixedly connected with one end of the first screw rod, and the second motor is fixed at one end of the positioning shell;

9. The control system of the four-freedom-degree space inspection mechanical arm according to claim 8, wherein one end, far away from the second motor, of the positioning shell is fixed with a guiding limiting piece, two ends of the sleeve are respectively fixed with a limiting piece, and the sleeve is fixed with a first linear guide rail arranged along the length direction of the sleeve; the guide limiting piece is connected to the first linear guide rail in a sliding mode.

10. The control system of the four-freedom-degree space inspection mechanical arm according to claim 8 or 9, wherein a dust cover is fixed on the second motor, the dust cover is sleeved on a section of the first screw close to the second motor, and the inner wall of the dust cover is rotatably connected with the first screw through a second bearing.

11. The control system of the four-freedom-degree space inspection mechanical arm according to claim 8 or 9, wherein one end, far away from the second motor, of the first screw rod is sleeved with a ball shaft sleeve, and the ball shaft sleeve is in rolling connection with the inner wall of the sleeve.

12. The control system of a spatial four-degree-of-freedom inspection robot according to any one of claims 1 to 4, 8 to 9, wherein the second rotary joint comprises a vertically arranged worm wheel, a worm meshed with the external teeth of the worm wheel, a casing, a third motor, and a second circular grating encoder for recording the rotation speed and position of the worm wheel; the outer side wall of the shell is fixed on one end of the telescopic arm far away from the first rotary joint, the third motor is fixed on the shell, a motor shaft of the third motor is fixedly connected with the worm in a coaxial way, and the position, close to the lower end, of the outer wall of the worm wheel is rotationally connected with the inner wall of the shell through an axial bearing; the circular grating ruler of the second circular grating encoder is coaxially fixed on the outer wall of the circumference side of the worm wheel, and the grating reading head of the circular grating ruler is fixed on the inner wall of the shell; the lower end of the worm wheel is fixedly connected with the upper end of the linear driving arm.

13. The control system of the four-freedom-degree space inspection mechanical arm according to claim 12, wherein the linear driving arm comprises a fourth motor, a shell, a second screw rod nut, a second linear guide rail and a second linear grating encoder for recording the position of the image acquisition device, the upper end of the shell is fixedly connected with the lower end of the worm wheel, and the fourth motor is fixed at the upper end of the shell; the second linear guide rail is fixed on the inner wall of the shell and is vertically arranged, the second lead screw is vertically arranged in the shell, the upper end of the second lead screw is coaxially and fixedly connected with the output shaft of the fourth motor, and the second lead screw nut is in threaded connection with the second lead screw and is in sliding connection with the second linear guide rail; the image acquisition device is fixed on one side wall of the screw nut, which is far away from the second linear guide rail.

14. The control system of the four-freedom-degree space inspection mechanical arm according to claim 13, wherein a through hole penetrating up and down is formed in the worm wheel, and the fourth motor is located in the through hole, and an output shaft of the fourth motor extends out of the lower end of the through hole and is fixedly connected with the upper end of the second screw rod.

15. The control system of the four-freedom-degree space inspection mechanical arm according to claim 13, wherein a cover body and a positioning block are respectively fixed on the inner sides of the upper end and the lower end of the shell, and the two ends of the second screw rod are respectively connected with the inner wall of the cover body and the positioning block in a rotating manner through a bidirectional bearing and a radial bearing.

16. The control system of a spatial four-degree-of-freedom inspection robot according to claim 1, further comprising: and the at least one isolation serial port unit is connected between the processing unit and the upper computer and is used for enabling the processing unit to carry out serial port communication with the upper computer.

17. The control system of a spatial four-degree-of-freedom inspection robot according to claim 1, further comprising: and the temperature acquisition unit is connected with the processing unit and is used for acquiring temperature information of the control system, and when the temperature information exceeds a preset temperature, the power supply of the control system is disconnected.

18. The control system of a spatial four-degree-of-freedom inspection robot according to claim 1, further comprising: and the storage unit is connected with the processing unit and used for storing the position information, the speed information and the current information.

19. A method for controlling a four-degree-of-freedom space inspection robot, which is characterized in that the method is realized by adopting the control system of the four-degree-of-freedom space inspection robot according to any one of claims 1 to 18, and comprises the following steps:

20. The method for controlling a four-degree-of-freedom space inspection robot according to claim 19, wherein the steps of obtaining position information of the inspection robot and controlling speed information and current information of a motor of the inspection robot include:

Receiving a control instruction sent by an upper computer;

21. The method for controlling a four-degree-of-freedom space inspection robot according to claim 20, wherein the calculating the control amount for controlling the movement of the inspection robot according to the processed position information, the processed speed information and the processed current information specifically comprises:

22. The method for controlling a spatial four-degree-of-freedom inspection robot according to any one of claims 19 to 21, further comprising:

and acquiring a temperature value of a control system for controlling the inspection mechanical arm, and switching off a power supply of the control system when the temperature value is larger than a preset temperature value.

23. The method for controlling a spatial four-degree-of-freedom inspection robot according to any one of claims 19 to 21, further comprising:

and acquiring and storing the position information, the speed information and the current information at preset time intervals.